Internals including trays, fillings, distributors and the like are installed inside easily polymerizeable substance treatment apparatuses (for example, distilling columns and absorption towers), which perform unit operations such as distillation, absorption and the like of easily polymerizeable substances, in order to increase the number of theoretical plates and enhance treatment efficiency. The trays have at least a portion of the upper surface being horizontal and through holes formed therein that penetrate the upper and lower surfaces, and are normally attached to a support beam.
Here, a support beam refers to a beam that supports or reinforces an internal, and is a long member having an internal mounting portion to which an internal is attached, and a folded-back portion in which the internal mounting portion is folded back. The support beam is installed within the easily polymerizeable substance treatment apparatus by the end(s) of the beam being fixed to the inside wall or support ring attached to the inside wall of the easily polymerizeable substance treatment apparatus.
In this support beam, the folded-back portion is provided to support or reinforce the internal mounting portion. Namely, as a result of having a folded-back portion, in addition to being able to adequately withstand the weight of the tray, the fixing surface area when the support beam is fixed to the easily polymerizeable substance treatment apparatus can be increased. In addition, the liquid flow of an easily polymerizeable substance is not obstructed as a result of the support beam being folded back with the folded-back portion.
FIG. 7 is a cross-sectional view showing an internal of an easily polymerizeable substance treatment apparatus and a support beam of the prior art. This support beam 30 has an internal mounting portion 32 where internal 31 is attached, a folded-back portion 33 in which the internal mounting portion 32 is folded back 180 degrees, and a connecting portion 34 that is perpendicular to internal mounting portion 32 and folded-back section 33, and connects one of their end portions along their lengthwise direction each other. Namely, this support beam has a U-shaped cross-portion when cut orthogonal to the lengthwise direction. Furthermore, such a support beam having a U-shaped cross portion is available commercially and can be acquired easily. In addition, this type of support beam having a U-shaped cross-portion facilitates fastening of an internal with bolts and nuts as compared with that in which internal mounting portion 32 and folded-back portion 33 are connected each other at both of their corresponding end portions along their lengthwise direction (support beam having a box-shaped (square-shaped) cross-portion).
Furthermore, as shown in Table 6-1 on page 331 of the Mechanical Design Handbook, 3rd edition, Mechanical Design Handbook Editorial Committee ed. (Maruzen Publishing), the shape of industrial support beams is such that the folded-back portion of a support beam having a U-shaped cross-portion is normally connected perpendicular to the connecting portion, namely horizontally.
However, in the case of treating an easily polymerizeable substance with a treatment apparatus equipped with a support beam of the prior art, the liquid of an easily polymerizeable substance tends to adhered to the upper surface of the folded-back portion of the support beam. Here, since the upper surface of the folded-back portion is horizontal, if the liquid of an easily polymerizeable substance becomes adhered thereto, it is difficult for the liquid to run off and the liquid remains there for a long period of time. Since the inside of an easily polymerizeable substance treatment apparatus is heated, in the case the liquid remains at the portion for a long period of time, the liquid of the easily polymerizeable substance accumulates heat and rises in temperature, thereby causing the easily polymerizeable substance to polymerize and form a polymer, after which polymerization progresses using that polymer as a starting point, and causes the polymer to gradually become larger.
In the case through holes serving as vapor-liquid flow paths for an easily polymerizeable substance are formed in an internal comprising an easily polymerizeable substance treatment apparatus, the polymer increases in size and ends up blocking the through holes. In this manner, in the case the through holes of an internal have been blocked, since the function as an internal decreases, this ultimately causes a decrease in the treatment efficiency of the easily polymerizeable substance.
Therefore, this is typically dealt with by injecting a polymerization inhibitor for preventing polymerization of the easily polymerizeable substance, or by increasing the amount injected of the inhibitor. However, it is necessary to inject a large amount of polymerization inhibitor in order to prevent polymerization at locations where liquid tends to be retained easily such as on the upper surface of the folded-back portion of the support beam, thereby making this uneconomical.
Furthermore, in the example shown in FIG. 7, although the internal and support beam are separate members, as shown in FIG. 8, there are also case in which the internal and support beam are in the form of an integral member 35. In this case as well, since the upper surface of folded-back portion 33 is horizontal, this member has the same problems as in the example shown in FIG. 7.
The present invention is achieved in consideration of the aforementioned circumstances, and the object of the present invention is to provide a support beam used for an easily polymerizeable substance treatment apparatus that economically prevents polymerization of the easily polymerizeable substance, and an easily polymerizeable substance treatment apparatus.